Weight limit recommendation in backpack use for school-aged children

By Valérie Lavigne

Valérie Lavigne, D.C., private chiropractic practice,Montreal, Quebec, Canada
Contact: valerielavigne@me.com or vlavigne@chirofamilial.com

Abstract
Background: Every day, children use backpacks to get their books back and forth from school. Many children carry very heavy backpacks and there are some concerns that this could be contributing to back pain in children.  Objective: The purpose of this paper is to assess, using the literature, what is the recommended weight limit that should be carried by school-aged children. Discussion: Many organizations, such as Back Pack Safety International, are trying to educate children on how to wear their backpacks properly and on the weight limit those children should carry to minimize back pain. However, many factors such as design, weight, how it is worn, and children’s physical fitness have been shown to have an influence on the development of pain caused by backpacks. As well, parents and teachers have a determining role in helping children be better organized to have lighter backpacks. The literature does not seem to agree on a set weight limit but it is shown that to prevent back pain it should definitely not exceed 10-15%. Conclusion: Backpacks have an influence on back pain in children and the weight limit should not exceed 10-15% of the child’s body weight.

Key words: backpack, back pain, school-aged, chiropractic

Introduction
Children around the world use backpacks to carry their school supplies to and from school.  Studies show that at least 90% of school children in the developed world are using backpacks every day1,2. The weight of backpacks carried by children is creating growing concerns amongst school administrators, parents and healthcare professionals3. Negrini and Carabalona (2002) reported that the average daily load of Italian students over a week ranged from 22% body weight (BW) to 27.5% BW with some students wearing backpacks weighing as much as 46% of their BW, exceeding the 30% bodyweight/load ratio proposed for physically fit adults4,5. Some researchers hypothesize that heavy backpacks may be contributing to back pain in school-aged children2,6 .

A child’s constantly developing spine experiences the highest rate of growth between the ages of 10-12 for girls and 13-15 for boys, with the secondary centers of ossification not fusing completely until the mid-twenties. At this stage, when the spine may be more susceptible to injury, proper backpack use is crucial to preventing postural deformities7,8.  As well, it is shown that by adding weight to the back with a backpack, the center of gravity is shifted forward toward the rear of the base of support. Postural compensations are needed to maintain balance and functional motion during gait; however, with improper loading of backpacks these postural compensations can result in injuries to the child’s spine.  Some of these compensations include an increased forward head carriage, an increase in forward lean of the trunk, as well as changes of pelvic positions and gait patters.  Grimmer et al. (2002) found that more than 20% of students in each age group had a mean change of 5° in craniovertebral angle (CVA) with the greatest changes in the smaller age group9,10. The degree of posture change in these children is comparable to the change in CVA in adult women suffering from headaches4.

To try to prevent back pain caused by backpack, backpack safety tips and information on choosing the right backpack, on how to fill it properly, and how to wear it correctly, are available from various website including the American Academy of Pediatrics11, The American Academy of Orthopedics12, Back Pack Safety International13, American Chiropractic Association14, and numerous other sites for parents, teachers and school-age kids4,15. Different methods of wearing backpacks have been recorded, for example some studies showed that 73.2% of students carried with one shoulder. This carrying method seems to be decreasing in the United States with the help of these backpack education programs that emphasize even weight distribution to avoid torqueing the spine4.

Back pain in school-age children is becoming a common complaint, with a prevalence ranging from 30%-65% 2,6,16. Unfortunately, some evidence in the literature shows that children suffering from low back pain may still have pain into adulthood; therefore, prevention is becoming important17-19. A factor contributing to this high prevalence of back pain in children stems from their increasingly sedentary lifestyle, with more time spent in front of the computer, television, etc. As well, there are some thoughts that the loading of the spine with backpacks every day is contributing to the issue2,5. It is believed that a certain amount of stress or load on the spine may contribute to its strength however, excessive and repetitive stress on a child’s body may result in overuse injuries.  Some injuries reported with backpack use are low back pain, neck pain, shoulder pain, muscle soreness, and rucksack palsy2. Other problems associated with backpack use have been reported, including respiratory problems, winged scapula, foot blisters, tripping accidents, and getting hit by the backpack20,21.  Siambanes et al (2004) surveyed 3498 Southern California adolescents and found that 41.3% reported pain when carrying backpacks, with 16.9% consulting a doctor for the pain and 16.1% reporting missing school activity due to pain22.  Korovessis et al. (2004) studied a sample of 3141 Greek students between 9 and 15 years old that showed an increase in dorsal pain correlated to increased backpack weight23.  It has also been reported that girls usually experience more pain with backpack use than boys4,15,24,25. It is important to note that these complications have not only been associated with the school bag load, but also with the duration that the school bag is carried. Increased duration will cause fatigue and pain; therefore, limiting only backpack weight may not be the solution5. The literature is unclear regarding the recommended weight for children -- there is some debate whether the cutoff should be no more than 10% of the BW or up to 15% of the BW.

This paper will review the literature to assess what is the recommended limit for backpack weight worn by school-age children.

Methods
The search was performed using PUBMEd with the following terms “backpacks and children” with limits of “review” and language “English”. This resulted in eight papers, which were all kept for analysis. A second search done using the terms with no limits “backpacks and children” revealed 60 articles – 14 were kept for references. The articles not kept did not discuss backpack weight limits specifically and were not retained. The articles were hand-searched and 3 more articles were retained. Evidence-based medicine (EBM) has a hierarchy that puts systematic reviews at the top of a pyramid followed by randomized control trials, cohort studies, case-control studies, case series, case reports and editorials and opinions26,27. The results of this search will be explained in order of highest evidence available according to EBM.

Results
Lindstrom-Hazel (2009) produced a systematic review of the literature looking to answer three questions. First, she asked, “Are school-age children at risk for back pain because of carrying backpacks? How much load is too much?”  Secondly, “Does backpack in adolescence predict back pain in adulthood? and thirdly “Are there behaviors that lessen/increase the risk of back pain/injury?”15.  The review was well performed with explained search methods and tables showing the relevant articles. The conclusions were that girls are more likely to experience back pain than boys, that the time carrying a pack may be a strong contributor to pain, and psychosomatic behavior may contribute to back pain. Lindstrom-Hazel (2009) reported that some authors were strongly calling for a weight limit; however, she believed that, up to this point, scientific studies had not yet produced consistent results that allowed her to wholeheartedly endorse safe limits that would protect all children. She believed that the issue of back pain was multifactorial including weight, time carried, and child’s height in relation to the backpack. She concluded that back pain in children was a strong predictor of back pain in adulthood. She also reported that, although many organizations have various recommendations for backpacks, many students still choose their pack according to color and size.  It can be assumed that many students do not understand the risk of back pain later in life; however, programs are in place to educate parents and teachers on avoiding unnecessary backpack weight. Therefore, according to this review, weight recommendations are not consistently supported to prevent back pain in children.

Brackley et Stevenson (2004) produced another systematic review trying to determine whether the suggested weight limit of 10-15% BW by certain organizations was the appropriate limit for school-age children and supported by the literature2. Their approach to the question was interesting because they separated the literature according to three different effects of backpacks use. They looked at the various literatures discussing the physiological consequences, the biomechanical consequences, and backpack design for children.  By looking at the effects of backpack use in different ways, this review was the most complete.  The search method was well explained and it included tables summarizing the research articles. The conclusion based on the literature, combining the three effects of backpack use, was that 10-15% BW is a justified weight limit. Further research is required to determine the association between backpacks and injury, and the way in which load, backpack design, as well as personal characteristics such as physical fitness, interact and influence adaptations required when carrying a backpack.

Kistner et al. (2012) looked at a small cohort study of 11 school children aged 8-11 years to examine the various effects of backpack loads on posture and postural compensations by evaluating forward head carriage4. The results showed immediate and statistically significant change in CVA, indicating increased forward head positions when using backpacks containing 15% and 20% BW. When students carried backpacks with 15% and 20% BW, more than 50% of the subjects reported discomfort after walking, with the neck as the primary location of reported pain.  The conclusion was that backpack loads should not exceed 10% BW due to the increased forward head position. One limitation to note from this study is the small sample size.

Rodriguez-Oviedo et al. (2012) produced a cross-sectional study in Spain that investigated whether backpack weight is associated with back pain and back pathology in school children25.  Their results showed that 61.4% of participants carried backpacks exceeding 10% BW and 18.1% exceeded 15% BW.  The children carrying the heaviest backpacks had a 50% higher risk of back pain and a 42% higher risk of pathology with girls showing a higher risk of back pain than boys. They encouraged the medical community to advice parents and school children about the risks posed by heavy school bags and the fact that this risk can be easily reduced.

Moore et al. (2007) produced a cohort study looking at 531 students in 5 different California schools from 5th to 12th grade and their backpack weights.  This study weighed the backpacks and students were then individually interviewed about how often they experienced pain while carrying a backpack, the site of their pain, and if it interfered with activities. The data supported the use of a 10% BW cutoff for safe backpack use for all grade levels and that girls were more at risk for back problems.

Discussion
When analyzing the literature regarding backpacks, it is challenging to recommend a weight limit that would prevent injury in all the children due to the multiple factors involved in the development of pain, i.e. design, weight, how it is worn, and children’s physical fitness.  Negrini et al. (2002) suggested time worn was also important to consider when analyzing the effects of backpacks5.  Macias et al. (2008) concluded that perceived pain in the low back was significantly higher while wearing the backpack on one shoulder versus two shoulders1. If one looks at the evidence, the systematic reviews (considered higher evidence in evidenced-based medicine) had conflicting conclusions and therefore were unable to suggest a clear weight limit. These reviews agree that more research is needed.  Smaller studies performed more recently point to a 10% BW but they are generally focusing on only one factor, such as biomechanical changes. There has been no research performed to date that considers all factors in their evaluation and analysis. It would be worth doing other studies, with more subjects, and analyzing many factors simultaneously to see if the 10% cut-off point should be recommended.

As chiropractors, it is important to incorporate questions regarding backpack use when taking the history of child. This information can help point the chiropractor towards some of the possible causes of back pain and should open up the discussion with the child and parent on how to carry books and appropriate weight limit. The chiropractors can then incorporate these recommendations when preparing the treatment plan of the child.  

Many people, including chiropractors, have a determining role in trying to reduce the weight children carry in their backpacks. Parents should be sensitized to the weight of the backpack as well as the distance the children walk to and from school, the design, and wearing technique of the backpack. Teachers can influence the children when it comes to what material needs to be brought home daily. They should be sensitized to the changes of posture created by poor backpack use so they understand the importance of proper use. When they are planning their weekly curriculum, they could do so according to the textbooks children will need on a specific day and assess what goes in the children’s backpack5. As part of the weekly routine, teachers could have a scale to weigh backpacks and encourage students to lighten their load. As well, to emphasize physical fitness along with a properly fitted backpack, physical education classes could include relay races while carrying the backpack.

In this era of technology, they can make use of e-books and reduce the number of textbooks needed with the use of smart tablets like the iPad.  A word of caution is needed here -- the use of computers by some schools has actually increased the load students’ carry because a specially designed backpack, which is already heavier, is required.  Before switching to digital textbooks, we need to ensure that technology does not, in fact, increase backpack weight. Students need to learn how to make good choices when loading their packs, including choosing to carry only things that are absolutely necessary and not everything they might need or want to bring home.  Furthermore, they should be taught to load bigger books in the back so to decrease stress on the shoulders. Parents should also make sure that the backpack contains no loose or dangling cords, strings and piece of clothing. These can catch while the child is walking, make them fall and create an injury that could be tragic if it caught in the door of the bus28.  With support from parents, the school curriculum should include a component of total backpack use including loading, lifting, holding, wearing, organizing, clearing and storing at school, to help prevent back pain in children.

Conclusion
It is evident that backpacks have an influence on back pain in children, but it is not clear if this pain is caused by weight alone or by multiple factors such as design, time worn, and physical fitness of child.  It seems difficult to design a backpack that would be suitable for all children and usable in every situation. It is fair to say that backpack weight should not exceed that maximum range of 10-15% BW, however the backpack weight appropriate for each child should be determined individually.

References:

  1. Macias BR, Murthy G, Chambers H, Hargens AR. Asymmetric loads and pain associated with backpack carrying by children. J. Pediatr Orthop Jul-Aug 2008;28(5):512-517.
    2.         Brackley HM, Stevenson JM. Are children's backpack weight limits enough? A critical review of the relevant literature. Spine (Phila Pa 1976). Oct 1 2004;29(19):2184-2190.
    3.         Moore MJ, White GL, Moore DL. Association of relative backpack weight with reported pain, pain sites, medical utilization, and lost school time in children and adolescents. J. Sch Health May 2007;77(5):232-239.
    4.         Kistner F, Fiebert I, Roach K. Effect of backpack load carriage on cervical posture in primary schoolchildren. Work 2012;41(1):99-108.
    5.         Negrini S, Carabalona R. Backpacks on! Schoolchildren's perceptions of load, associations with back pain and factors determining the load. Spine (Phila Pa 1976. Jan 15 2002;27(2):187-195.
    6.         Malleson P, Clinch J. Pain syndromes in children. Curr Opin Rheumatol Sep 2003;15(5):572-580.
    7.         Ramprasad M, Alias J, Raghuveer AK. Effect of backpack weight on postural angles in preadolescent children. Indian Pediatr Jul 2010;47(7):575-580.
    8.         De Paula AJ, Silva JC, Paschoarelli LC, Fujii JB. Backpacks and school children's obesity: challenges for public health and ergonomics. Work 2012;41 Suppl 1:900-906.
    9.         Grimmer K, Dansie B, Milanese S, Pirunsan U, Trott P. Adolescent standing postural response to backpack loads: a randomised controlled experimental study. BMC Musculoskelet Disord Apr 17 2002;3:10.
    10.        Grimmer KA, Williams MT, Gill TK. The associations between adolescent head-on-neck posture, backpack weight, and anthropometric features. Spine (Phila Pa 1976) Nov 1 1999;24(21):2262-2267.
    11.        American Academy of Pediatrics. Backpack Safety. 2013; http://www.healthychildren.org/English/safety-prevention/at-play/Pages/Backpack-Safety.aspx?nfstatus=401&nftoken=00000000-0000-0000-0000-000000000000&nfstatusdescription=ERROR%3a+No+local+token . Accessed June 6, 2013.
    12.        American Academy of Orthopaedic Surgeons. Backpack Safety. 2011; http://www.healthychildren.org/English/safety-prevention/at-play/Pages/Backpack-Safety.aspx?nfstatus=401&nftoken=00000000-0000-0000-0000-000000000000&nfstatusdescription=ERROR%3a+No+local+token . Accessed June 6, 2013.
    13.        Back Pack Safety International. 2013; http://www.backpacksafe.com . Accessed Nov 6, 2013.
    14.        American Chiropractic Association. Backpack Misuse Leads to Chronic Back Pain, Doctors of Chiropractic Say. 2013; http://www.acatoday.org/content_css.cfm?CID=65 . Accessed Nov 6, 2013, 2013.
    15.        Lindstrom-Hazel D. The backpack problem is evident but the solution is less obvious. Work 2009;32(3):329-338.
    16.        Haselgrove C, Straker L, Smith A, O'Sullivan P, Perry M, Sloan N. Perceived school bag load, duration of carriage, and method of transport to school are associated with spinal pain in adolescents: an observational study. Aust J Physiother 2008;54(3):193-200.
    17.        Hestbaek L, Leboeuf-Yde C, Kyvik KO. Is comorbidity in adolescence a predictor for adult low back pain? A prospective study of a young population. BMC Musculoskelet Disord 2006;7:29.
    18.        Hestbaek L, Leboeuf-Yde C, Kyvik KO, Manniche C. The course of low back pain from adolescence to adulthood: eight-year follow-up of 9600 twins. Spine (Phila Pa 1976) Feb 15 2006;31(4):468-472.
    19.        Brattberg G. Do pain problems in young school children persist into early adulthood? A 13-year follow-up. Eur J Pain Jun 2004;8(3):187-199.
    20.        Wiersema BM, Wall EJ, Foad SL. Acute backpack injuries in children. Pediatrics Jan 2003;111(1):163-166.
    21.        Golriz S, Walker B. Backpacks. Several factors likely to influence design and usage: a systematic literature review. Work 2012;42(4):519-531.
    22.        Siambanes D, Martinez JW, Butler EW, Haider T. Influence of school backpacks on adolescent back pain. J. Pediatr. Orthop Mar-Apr 2004;24(2):211-217.
    23.        Korovessis P, Koureas G, Papazisis Z. Correlation between backpack weight and way of carrying, sagittal and frontal spinal curvatures, athletic activity, and dorsal and low back pain in schoolchildren and adolescents. J Spinal Disord Tech Feb 2004;17(1):33-40.
    24.        Talbott NR, Bhattacharya A, Davis KG, Shukla R, Levin L. School backpacks: it's more than just a weight problem. Work 2009;34(4):481-494.
    25.        Rodriguez-Oviedo P, Ruano-Ravina A, Perez-Rios M, et al. School children's backpacks, back pain and back pathologies. Arch Dis Child Aug 2012;97(8):730-732.
    26.        Haneline M. Steps involved in the practice of evidence-based chiropractic. Evidence-Based Chiropractic Practice: Jones and Bartlett Publishers; 2007:25.
    27.        Centre for Evidence Based Medecine. Levels of Evidence. 2009; http://www.cebm.net/?o=1025 . Accessed November 17, 2013.
    28.        Dale JC. School backpacks: preventing injuries. J. Pediatr Health Care Sep-Oct 2004;18(5):264-266.